Heat Exchanger Elevated Temperature Protection Sleeve

ABSTRACT

A heating, ventilation, and/or air conditioning (HVAC) system may include a furnace having at least one heat exchanger tube with a temperature protection sleeve at least partially disposed in the heat exchanger tube. The temperature protection sleeve includes a flange, an elongated tubular portion extending from the flange, and a plurality of perforations disposed about the elongated tubular portion. The temperature protection sleeve protects the heat exchanger tube from high flame temperatures or elevated temperature flue products caused by rapidly combusting a pre-mixed air-fuel mixture within a burner of the furnace, thereby allowing the heat exchanger tube to comply with ANSI Z21.47. The furnace provides less than 14 Nanograms of oxides of nitrogen per Joule (Ng/J) of heat delivered to a temperature conditioned area and complies with SCAQMD Rule 1111.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Heating, ventilation, and/or air conditioning (HVAC) systems used incommercial and residential applications often include a furnace havingat least one heat exchanger configured to promote heat transfer with anairflow that contacts the heat exchanger to provide a heated airflow tocondition an interior space. Traditional gas-fired heat exchangers usedin furnaces may employ a long flame burner and/or multiple long flameburners to distribute heat over the heat exchanger slowly and/or evenly.However, this slow combustion process may produce excess emissions thatdo not comply with required standards for residential and/or commercialHVAC system applications.

SUMMARY

In some embodiments of the disclosure, a heat exchanger for a furnace isdisclosed as comprising: at least one heat exchanger tube; and atemperature protection sleeve disposed at least partially within theheat exchanger tube.

In other embodiments of the disclosure, a furnace is disclosed ascomprising: at least one burner; and a heat exchanger, comprising: atleast one heat exchanger tube; and a temperature protection sleevedisposed at least partially within the heat exchanger tube.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description:

FIG. 1 is a schematic diagram of an HVAC system according to anembodiment of the disclosure;

FIG. 2 is a schematic diagram of air circulation paths of a structureconditioned by two HVAC systems of FIG. 1 according to an embodiment ofthe disclosure;

FIG. 3 is a schematic view of a furnace comprising a heat exchanger tubeand a temperature protection sleeve according to an embodiment of thedisclosure;

FIG. 4 is partial detailed view of the heat exchanger tube and thetemperature protection sleeve of FIG. 3 according to an embodiment ofthe disclosure;

FIG. 5 is a detailed view of the temperature protection sleeve of FIGS.3 and 4 according to an embodiment of the disclosure; and

FIG. 6 is a schematic diagram of the temperature protection sleeve ofFIG. 5 according to an embodiment of the disclosure.

DETAILED DESCRIPTION

Referring now to FIG. 1, a schematic diagram of an HVAC system 100according to an embodiment of this disclosure is shown. HVAC system 100comprises an indoor unit 102, an outdoor unit 104, and a systemcontroller 106. In some embodiments, the system controller 106 mayoperate to control operation of the indoor unit 102 and/or the outdoorunit 104. As shown, the HVAC system 100 is a so-called heat pump systemthat may be selectively operated to implement one or more substantiallyclosed thermodynamic refrigeration cycles to provide a coolingfunctionality and/or a heating functionality. In alternativeembodiments, the HVAC system 100 may comprise a type of air-conditioningsystem that is not a heat pump system.

Indoor unit 102 comprises an indoor heat exchanger 108, an indoor fan110, and an indoor metering device 112. Indoor heat exchanger 108 is aplate fin heat exchanger configured to allow heat exchange betweenrefrigerant carried within internal tubing of the indoor heat exchanger108 and fluids that contact the indoor heat exchanger 108 but that arekept segregated from the refrigerant. In other embodiments, indoor heatexchanger 108 may comprise a spine fin heat exchanger, a microchannelheat exchanger, or any other suitable type of heat exchanger.

The indoor fan 110 is a centrifugal blower comprising a blower housing,a blower impeller at least partially disposed within the blower housing,and a blower motor configured to selectively rotate the blower impeller.In other embodiments, the indoor fan 110 may comprise a mixed-flow fanand/or any other suitable type of fan. The indoor fan 110 is configuredas a modulating and/or variable speed fan capable of being operated atmany speeds over one or more ranges of speeds. In other embodiments, theindoor fan 110 may be configured as a multiple speed fan capable ofbeing operated at a plurality of operating speeds by selectivelyelectrically powering different ones of multiple electromagneticwindings of a motor of the indoor fan 110. In yet other embodiments, theindoor fan 110 may be a single speed fan.

The indoor metering device 112 is an electronically controlled motordriven electronic expansion valve (EEV). In alternative embodiments, theindoor metering device 112 may comprise a thermostatic expansion valve,a capillary tube assembly, and/or any other suitable metering device.The indoor metering device 112 may comprise and/or be associated with arefrigerant check valve and/or refrigerant bypass for use when adirection of refrigerant flow through the indoor metering device 112 issuch that the indoor metering device 112 is not intended to meter orotherwise substantially restrict flow of the refrigerant through theindoor metering device 112.

Outdoor unit 104 comprises an outdoor heat exchanger 114, a compressor116, an outdoor fan 118, an outdoor metering device 120, and a reversingvalve 122. Outdoor heat exchanger 114 is a spine fin heat exchangerconfigured to allow heat exchange between refrigerant carried withininternal passages of the outdoor heat exchanger 114 and fluids thatcontact the outdoor heat exchanger 114 but that are kept segregated fromthe refrigerant. In other embodiments, outdoor heat exchanger 114 maycomprise a plate fin heat exchanger, a microchannel heat exchanger, orany other suitable type of heat exchanger.

The compressor 116 is a multiple speed scroll type compressor configuredto selectively pump refrigerant at a plurality of mass flow rates. Inalternative embodiments, the compressor 116 may comprise a modulatingcompressor capable of operation over one or more speed ranges, thecompressor 116 may comprise a reciprocating type compressor, thecompressor 116 may be a single speed compressor, and/or the compressor116 may comprise any other suitable refrigerant compressor and/orrefrigerant pump.

The outdoor fan 118 is an axial fan comprising a fan blade assembly andfan motor configured to selectively rotate the fan blade assembly. Inother embodiments, the outdoor fan 118 may comprise a mixed-flow fan, acentrifugal blower, and/or any other suitable type of fan and/or blower.The outdoor fan 118 is configured as a modulating and/or variable speedfan capable of being operated at many speeds over one or more ranges ofspeeds. In other embodiments, the outdoor fan 118 may be configured as amultiple speed fan capable of being operated at a plurality of operatingspeeds by selectively electrically powering different ones of multipleelectromagnetic windings of a motor of the outdoor fan 118. In yet otherembodiments, the outdoor fan 118 may be a single speed fan.

The outdoor metering device 120 is a thermostatic expansion valve. Inalternative embodiments, the outdoor metering device 120 may comprise anelectronically controlled motor driven EEV, a capillary tube assembly,and/or any other suitable metering device. The outdoor metering device120 may comprise and/or be associated with a refrigerant check valveand/or refrigerant bypass for use when a direction of refrigerant flowthrough the outdoor metering device 120 is such that the outdoormetering device 120 is not intended to meter or otherwise substantiallyrestrict flow of the refrigerant through the outdoor metering device120.

The reversing valve 122 is a so-called four-way reversing valve. Thereversing valve 122 may be selectively controlled to alter a flowpath ofrefrigerant in the HVAC system 100 as described in greater detail below.The reversing valve 122 may comprise an electrical solenoid or otherdevice configured to selectively move a component of the reversing valve122 between operational positions.

The system controller 106 may comprise a touchscreen interface fordisplaying information and for receiving user inputs. The systemcontroller 106 may display information related to the operation of theHVAC system 100 and may receive user inputs related to operation of theHVAC system 100. However, the system controller 106 may further beoperable to display information and receive user inputs tangentiallyand/or unrelated to operation of the HVAC system 100. In someembodiments, the system controller 106 may comprise a temperature sensorand may further be configured to control heating and/or cooling of zonesassociated with the HVAC system 100. In some embodiments, the systemcontroller 106 may be configured as a thermostat for controlling supplyof conditioned air to zones associated with the HVAC system 100.

In some embodiments, the system controller 106 may selectivelycommunicate with an indoor controller 124 of the indoor unit 102, withan outdoor controller 126 of the outdoor unit 104, and/or with othercomponents of the HVAC system 100. In some embodiments, the systemcontroller 106 may be configured for selective bidirectionalcommunication over a communication bus 128. In some embodiments,portions of the communication bus 128 may comprise a three-wireconnection suitable for communicating messages between the systemcontroller 106 and one or more of the HVAC system 100 componentsconfigured for interfacing with the communication bus 128. Stillfurther, the system controller 106 may be configured to selectivelycommunicate with HVAC system 100 components and/or other device 130 viaa communication network 132. In some embodiments, the communicationnetwork 132 may comprise a telephone network and the other device 130may comprise a telephone. In some embodiments, the communication network132 may comprise the Internet and the other device 130 may comprise aso-called smartphone and/or other Internet enabled mobiletelecommunication device.

The indoor controller 124 may be carried by the indoor unit 102 and maybe configured to receive information inputs, transmit informationoutputs, and otherwise communicate with the system controller 106, theoutdoor controller 126, and/or any other device 130 via thecommunication bus 128 and/or any other suitable medium of communication.In some embodiments, the indoor controller 124 may be configured tocommunicate with an indoor personality module 134, receive informationrelated to a speed of the indoor fan 110, transmit a control output toan electric heat relay, transmit information regarding an indoor fan 110volumetric flow-rate, communicate with and/or otherwise affect controlover an air cleaner 136, and communicate with an indoor EEV controller138. In some embodiments, the indoor controller 124 may be configured tocommunicate with an indoor fan controller 142 and/or otherwise affectcontrol over operation of the indoor fan 110. In some embodiments, theindoor personality module 134, or any other suitable information storagedevice, may comprise information related to the identification and/oroperation of the indoor unit 102 and/or a position of the outdoormetering device 120.

In some embodiments, the indoor EEV controller 138 may be configured toreceive information regarding temperatures and pressures of therefrigerant in the indoor unit 102. More specifically, the indoor EEVcontroller 138 may be configured to receive information regardingtemperatures and pressures of refrigerant entering, exiting, and/orwithin the indoor heat exchanger 108. Further, the indoor EEV controller138 may be configured to communicate with the indoor metering device 112and/or otherwise affect control over the indoor metering device 112.

The outdoor controller 126 may be carried by the outdoor unit 104 andmay be configured to receive information inputs, transmit informationoutputs, and otherwise communicate with the system controller 106, theindoor controller 124, and/or any other device 130 via the communicationbus 128 and/or any other suitable medium of communication. In someembodiments, the outdoor controller 126 may be configured to communicatewith an outdoor personality module 140 that may comprise informationrelated to the identification and/or operation of the outdoor unit 104.In some embodiments, the outdoor controller 126 may be configured toreceive information related to an ambient temperature associated withthe outdoor unit 104, information related to a temperature of theoutdoor heat exchanger 114, and/or information related to refrigeranttemperatures and/or pressures of refrigerant entering, exiting, and/orwithin the outdoor heat exchanger 114 and/or the compressor 116. In someembodiments, the outdoor controller 126 may be configured to transmitinformation related to monitoring, communicating with, and/or otherwiseaffecting control over the outdoor fan 118, a compressor sump heater, asolenoid of the reversing valve 122, a relay associated with adjustingand/or monitoring a refrigerant charge of the HVAC system 100, aposition of the indoor metering device 112, and/or a position of theoutdoor metering device 120. The outdoor controller 126 may further beconfigured to communicate with a compressor drive controller 144 that isconfigured to electrically power and/or control the compressor 116.

The HVAC system 100 is shown configured for operating in a so-calledcooling mode in which heat is absorbed by refrigerant at the indoor heatexchanger 108 and heat is rejected from the refrigerant at the outdoorheat exchanger 114. In some embodiments, the compressor 116 may beoperated to compress refrigerant and pump the relatively hightemperature and high pressure compressed refrigerant from the compressor116 to the outdoor heat exchanger 114 through the reversing valve 122and to the outdoor heat exchanger 114. As the refrigerant is passedthrough the outdoor heat exchanger 114, the outdoor fan 118 may beoperated to move air into contact with the outdoor heat exchanger 114,thereby transferring heat from the refrigerant to the air surroundingthe outdoor heat exchanger 114. The refrigerant may primarily compriseliquid phase refrigerant and the refrigerant may be pumped from theoutdoor heat exchanger 114 to the indoor metering device 112 throughand/or around the outdoor metering device 120 which does notsubstantially impede flow of the refrigerant in the cooling mode. Theindoor metering device 112 may meter passage of the refrigerant throughthe indoor metering device 112 so that the refrigerant downstream of theindoor metering device 112 is at a lower pressure than the refrigerantupstream of the indoor metering device 112. The pressure differentialacross the indoor metering device 112 allows the refrigerant downstreamof the indoor metering device 112 to expand and/or at least partiallyconvert to a gaseous phase. The gaseous phase refrigerant may enter theindoor heat exchanger 108. As the refrigerant is passed through theindoor heat exchanger 108, the indoor fan 110 may be operated to moveair into contact with the indoor heat exchanger 108, therebytransferring heat to the refrigerant from the air surrounding the indoorheat exchanger 108. The refrigerant may thereafter reenter thecompressor 116 after passing through the reversing valve 122.

To operate the HVAC system 100 in the so-called heating mode, thereversing valve 122 may be controlled to alter the flowpath of therefrigerant, the indoor metering device 112 may be disabled and/orbypassed, and the outdoor metering device 120 may be enabled. In theheating mode, refrigerant may flow from the compressor 116 to the indoorheat exchanger 108 through the reversing valve 122, the refrigerant maybe substantially unaffected by the indoor metering device 112, therefrigerant may experience a pressure differential across the outdoormetering device 120, the refrigerant may pass through the outdoor heatexchanger 114, and the refrigerant may reenter the compressor 116 afterpassing through the reversing valve 122. Most generally, operation ofthe HVAC system 100 in the heating mode reverses the roles of the indoorheat exchanger 108 and the outdoor heat exchanger 114 as compared totheir operation in the cooling mode.

Referring now to FIG. 2, a schematic diagram of air circulation paths ofa structure 250 conditioned by two HVAC systems 100 is shown. In thisembodiment, the structure 250 is conceptualized as comprising a lowerfloor 222 and an upper floor 224. The lower floor 222 comprises zones226, 228, and 230 while the upper floor 224 comprises zones 232, 234,and 236. The HVAC system 100 associated with the lower floor 222 isconfigured to circulate and/or condition air of lower zones 226, 228,and 230 while the HVAC system 100 associated with the upper floor 224 isconfigured to circulate and/or condition air of upper zones 232, 234,and 236.

In addition to the components of HVAC system 100 described above, inthis embodiment, each HVAC system 100 further comprises a ventilator146, a prefilter 148, a humidifier 150, and a bypass duct 152. Theventilator 146 may be operated to selectively exhaust circulating air tothe environment and/or introduce environmental air into the circulatingair. The prefilter 148 may generally comprise a filter media selected tocatch and/or retain relatively large particulate matter prior to airexiting the prefilter 148 and entering the air cleaner 136. Thehumidifier 150 may be operated to adjust a humidity of the circulatingair. The bypass duct 152 may be utilized to regulate air pressureswithin the ducts that form the circulating air flowpaths. In someembodiments, air flow through the bypass duct 152 may be regulated by abypass damper 154 while air flow delivered to the zones 226, 228, 230,232, 234, and 236 may be regulated by zone dampers 156.

Still further, each HVAC system 100 may further comprise a zonethermostat 158 and a zone sensor 160. In some embodiments, a zonethermostat 158 may communicate with the system controller 106 and mayallow a user to control a temperature, humidity, and/or otherenvironmental setting for the zone in which the zone thermostat 158 islocated. Further, the zone thermostat 158 may communicate with thesystem controller 106 to provide temperature, humidity, and/or otherenvironmental feedback regarding the zone in which the zone thermostat158 is located. In some embodiments, a zone sensor 160 may communicatewith the system controller 106 to provide temperature, humidity, and/orother environmental feedback regarding the zone in which the zone sensor160 is located.

While the HVAC systems 100 are shown as so-called split systemscomprising an indoor unit 102 located separately from the outdoor unit104, alternative embodiments of an HVAC system 100 may comprise aso-called package system in which one or more of the components of theindoor unit 102 and one or more of the components of the outdoor unit104 are carried together in a common housing or package. The HVACsystems 100 are shown as a so-called ducted system where the indoor unit102 is located remote from the conditioned zones, thereby requiring airducts to route the circulating air. However, in alternative embodiments,an HVAC systems 100 may be configured as non-ducted systems in which theindoor unit 102 and/or multiple indoor units 102 associated with anoutdoor unit 104 are located substantially in the space and/or zone tobe conditioned by the respective indoor units 102, thereby not requiringair ducts to route the air conditioned by the indoor units 102.

Furthermore, the system controllers 106 may be configured forbidirectional communication with each other and may further beconfigured so that a user may, using any of the system controllers 106,monitor and/or control any of the HVAC system 100 components regardlessof which zones the components may be associated. Further, each systemcontroller 106, each zone thermostat 158, and each zone sensor 160 maycomprise a humidity sensor. As such, it will be appreciated thatstructure 250 is equipped with a plurality of humidity sensors in aplurality of different locations. In some embodiments, a user mayeffectively select which of the plurality of humidity sensors is used tocontrol operation of one or more of the HVAC systems 100. In someembodiments, the HVAC systems 100 may further comprise a furnace 170configured to burn fuel such as, but not limited to, natural gas,heating oil, propane, and/or any other suitable fuel, to generate heatand/or provide heated air to at least one zone 226, 228, 230, 232, 234,236 conditioned by an HVAC system 100.

Referring now to FIG. 3, a schematic view of a furnace 170 is shownaccording to an embodiment of the disclosure. In this embodiment, thefurnace 170 may be configured as a non-condensing gas-fired furnace.Furnace 170 generally comprises a furnace cabinet 172, a partition panel173 that defines an interior space 188 of the furnace 170, a burner box174 comprising at least one or more burners configured to receive andrapidly combust a pre-mixed air-fuel mixture, and a draft inducer system184 configured to draw the at least partially combusted air-fuel mixturefrom the burner box 174 through at least one heat exchanger tube 200before ejecting the at least partially combusted air-fuel mixturethrough an exhaust 186. Additionally, as will be discussed later hereinin more detail, the furnace 170 and/or the heat exchanger tube 200 mayalso comprise a temperature protection sleeve 250 disposed within theheat exchanger tube 200.

The heat exchanger tube 200 generally comprises an inlet 201 configuredto receive hot gases produced from at least partially combusting theair-fuel mixture, a first pass 202, a second pass 204, a third pass 206,a fourth pass 208, and an outlet 209 coupled to the partition panel 173and/or the draft inducer system 184. The first pass 202 is coupled tothe second pass 204 by a first bend 203, the second pass 204 is coupledto the third pass 206 by a second bend 205, and the third pass 206 iscoupled to the fourth pass 208 by a third bend 207 to form a continuousinternal fluid flow path that extends from the inlet 201 associated withan open end of the first pass 202, through internal passages of each ofthe first pass 202, first bend 203, second pass 204, second bend 205,third pass 206, third bend 207, and fourth pass 208, to an outlet 209associated with an open end of the fourth pass 208. Furnaces withgreater than 80% AFUE may incorporate secondary heat exchangersreplacing pass 208 comprised of materials capable of extended exposureto products of combustion including mildly acidic liquids which are theresult of products of combustion reaching temperatures lower than dewpoint (saturation).

It will be appreciated that the passes 202, 204, 206, 208 generally maycomprise substantially straight tubes that may be oriented substantiallyparallel to each other, such that the bends 203, 205, 207 generallycomprise 180 degree U-shaped bends. Accordingly, each heat exchangertube 200 may generally pass multiple times across the interior space 188of the furnace 170. However, the first pass 202 may or may not generallycomprise tapered swage joints at each end that taper into a largerdiameter or alternative geometry tube of the first pass 202.Accordingly, the first pass 202 may comprise a first tapered swage joint202 a that extends from the inlet 201 to a constant diameter portion 202b of the first pass 202 and a second tapered swage joint 202 c thatextends from the constant diameter portion 202 b to the first bend 203.Additionally, the interior space 188 of the furnace 170 may beconfigured to receive an incoming airflow 190 generated by a blower ofthe furnace 170 and/or the indoor fan 110 of the indoor unit 102 of FIG.1, so that the incoming airflow 190 may contact each of the passes 202,204, 206, 208 and/or bends 203, 205, 207 to promote heat transferbetween fluid and/or hot gases within the internal passages of the heatexchanger tube 200 and the incoming airflow 190.

While only one heat exchanger tube 200 is shown, additional heatexchanger tubes 200 may be utilized to increase an overall heatingcapacity. Thus, a plurality of heat exchanger tubes 200 may receive hotgases produced by at least partially combusting the air-fuel mixturewithin the burner box 174 and/or each of the burners associated with theburner box 174. In some embodiments, a plurality of heat exchanger tubes200 may receive the hot gases produced by at least partially combustingthe air-fuel mixture from an associated and/or dedicated burner of theburner box 174, so that multiple parallel hot gas flow paths may beformed through the heat exchanger tubes 200 of the furnace 170. However,in other embodiments, the burners may feed at least one manifoldconfigured to distribute the hot gases to the plurality of heatexchanger tubes 200. Further, the flow of the hot gases through the heatexchanger tubes 200 produced from at least partially combusting theair-fuel mixture may be provided by the draft inducer system 184 beforeejecting the hot gases through the exhaust 186. Still further, while thefurnace 170 is disclosed as a so-called non-condensing furnacecomprising at least one heat exchanger tube 200, alternative furnace 170embodiments may be a so-called condensing furnace and comprise at leastone heat exchanger tube 200 and at least one secondary heat exchangerconnected to the heat exchanger tube 200 by a hot header.

Referring now to FIGS. 4 and 5, a partial detailed view of the heatexchanger tube 200 and the temperature protection sleeve 250 of FIG. 3,and a detailed view of the temperature protection sleeve 250 of FIGS. 3and 4 are shown, respectively, according to an embodiment of thedisclosure. As stated, the burner box 174 is configured to receive apre-mixed air-fuel mixture. The pre-mixed air-fuel mixture may generallycombust within the burner box 174 very rapidly. The rapid, almostinstant combustion occurs because the pre-mixed air-fuel mixtureenhances atomization of the fuel, thereby producing a very rapidcombustion process. As a result of the rapid combustion process, heatreleased from the combusted fuel also occurs rapidly, producing flametemperatures that are significantly higher as compared to other burnersthat employ external secondary forms of aeration or that mix the air andfuel during combustion. The quick heat release and increased flametemperatures may cause damage to joints (tapered swage joints 202 a, 202c) of the heat exchanger tube 200 and/or the heat exchanger tube 200itself. Accordingly, heat exchanger tube 200 comprises a temperatureprotection sleeve 250 configured to protect the heat exchanger tube 200from the quick heat release and increased flame temperatures produced asa result of the rapid combustion of the pre-mixed air-fuel mixture.

The temperature protection sleeve 250 comprises an inlet 252, a flange254, an elongated tube 256 that extends from the flange 254, and anoutlet 258. Additionally, in some embodiments, the temperatureprotection sleeve 250 may also comprise a plurality of perforations 260disposed about the elongated tube 256. Most generally, the temperatureprotection sleeve 250 may be disposed locally to the combustion processto provide the greatest amount of protection to the heat exchanger tube200. In this embodiment, the temperature protection sleeve 250 may bedisposed at least partially within the inlet 201 of the heat exchangertube 200. The temperature protection sleeve 250 may comprise acompression and/or an interference fit with the inlet 201 of the heatexchanger tube 200 to retain the temperature protection sleeve 250within the heat exchanger tube 200. Additionally, when the temperatureprotection sleeve 250 is captured inside the inlet 201 of the heatexchanger tube 200, the flange 254 of the temperature protection sleeve250 may be rolled, formed, and/or otherwise manipulated around the inlet201 of the heat exchanger tube 200 to secure the temperature protectionsleeve 250 to the heat exchanger tube 200.

The temperature protection sleeve 250 may generally be formed from amaterial that promotes a gradual distribution of heat. Accordingly, thetemperature protection sleeve 250 may generally be formed a compositematerial. In some embodiments, the temperature protection sleeve 250 maybe formed from an alumina-fiber material (e.g. high grade fiberglassmaterial). However, in other embodiments, the temperature protectionsleeve 250 may be formed from a carbon fiber and/or any other metallicfiber composite suitable for subjection to significant flametemperatures produced by rapid combustion of a pre-mixed air-fuelmixture. Accordingly, the temperature protection sleeve 250 may beconfigured to shield the inlet 201, the vulnerable tapered swage joints202 a, 202 c of the first pass 202, and/or the constant diameter portion202 b of the first pass 202 from the increased flame temperaturesproduced by rapid combustion of a pre-mixed air-fuel mixture.

In some embodiments, the temperature protection sleeve 250 may protectthe vulnerable areas of the heat exchanger tube 200 by promoting gradualheat transfer in those areas. Further, in some embodiments, thetemperature protection sleeve 250 may prevent the high temperature flamefrom directly contacting the first tapered swage joint 202 a between thepartition panel 173 and the constant diameter portion 202 b of the firstpass 202. Thus, in some embodiments, the protection provided by thetemperature protection sleeve 250 may be a result of diffusing the localhigh temperature flame and/or released heat caused by rapidly combustingthe pre-mixed air-fuel mixture. As such, in some embodiments, the localhigh temperature flame and/or released heat may be passed through theinternal passage of the temperature protection sleeve 250, where it mayslowly diffuse and/or pass through the perforations 260 of thetemperature protection sleeve 250. Additionally, in some embodiments,tertiary air, such as non-combustion air may be introduced into thetemperature protection sleeve 250 through the perforations 260 to aid inthe heat distribution provided by the temperature protection sleeve 250.By slowly diffusing the heat produced, the first pass 202 of the heatexchanger tube 200 may experience a more gradual, even, and/or uniformtemperature distribution across the length of the first pass 202,thereby increasing and/or maximizing heat transfer with the incomingairflow 190 that contacts the first pass 202. Further, by thetemperature protection sleeve 250 distributing the heat more evenlythroughout the first pass 202, the heat may also be distributed moreevenly throughout the entire heat exchanger tube 200, thereby increasingthe overall heat transfer properties of the entire heat exchanger tube200.

As a result of slowly and/or more evenly distributing and/or diffusingthe heat throughout the heat exchanger tube 200 caused by thetemperature protection sleeve 250, the temperature protection sleeve 250enables the heat exchanger tube 200 and/or furnace 170 to maintaintemperatures compliant with applicable heat standards for gas-firedfurnaces, such as ANSI Z21.47-2016 CSA 2.3 2016 section 5.16-18 andreferenced section 4.2.7 Table 1. At least in some part, the materialselection of the temperature protection sleeve 250 contributes to theheat exchanger tube 200 complying with ANSI Z21.47. Furthermore, becauseof the rapid combustion of the pre-mixed air-fuel mixture, thecombustion results in extremely low Nitrogen Oxide (NOx) emissions. Insome embodiments, the NOx emissions may be less than 14 Nanograms ofNitrogen Oxides (calculated as Nanograms per Joule (Ng/J) of useful heatdelivered to the temperature conditioned area. Accordingly, a furnace170 comprising the heat exchanger tube 200 and the temperatureprotection sleeve 250 may comply with SCAQMD Rule 1111.

Referring now to FIG. 6, a schematic diagram 300 of the temperatureprotection sleeve 250 of FIGS. 3-5 is shown according to an embodimentof the disclosure. The schematic diagram 300 illustrates that byproviding the temperature protection sleeve 250 in the heat exchangertube 200, the heat exchanger tube 200 and/or the furnace 170 iscompliant with the ANSI Z21.47 material temperature standard since thetemperature protection sleeve 250 protects the heat exchanger tube 200from the high temperature flame that typically would damage heattransfer components when a pre-mixed air-fuel mixture is rapidlycombusted. Additionally, because the rapid combustion produces low NOxemissions (at least less than 14 Ng/J), the furnace 170 also complieswith SCAQMD Rule 1111. As such, heat transfer between the heat exchangertube 200 and the incoming airflow 190 may be maximized to provide anefficiently heated airflow to at least one of the temperatureconditioned areas (e.g. zones 226, 228, 230, 232, 234, 236). Thus, thetemperature protection sleeve 250 enables compliance of the furnace 170with both the ANSI Z21.47 material temperature standard and SCAQMD Rule1111.

At least one embodiment is disclosed and variations, combinations,and/or modifications of the embodiment(s) and/or features of theembodiment(s) made by a person having ordinary skill in the art arewithin the scope of the disclosure. Alternative embodiments that resultfrom combining, integrating, and/or omitting features of theembodiment(s) are also within the scope of the disclosure. Wherenumerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example,whenever a numerical range with a lower limit, R_(l), and an upperlimit, R_(u), is disclosed, any number falling within the range isspecifically disclosed. In particular, the following numbers within therange are specifically disclosed: R=R_(l)+k*(R_(u)−R_(l)), wherein k isa variable ranging from 1 percent to 100 percent with a 1 percentincrement, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent,96 percent, 97 percent, 98 percent, 99 percent, or 100 percent.

Unless otherwise stated, the term “about” shall mean plus or minus 10percent of the subsequent value. Moreover, any numerical range definedby two R numbers as defined in the above is also specifically disclosed.Use of the term “optionally” with respect to any element of a claimmeans that the element is required, or alternatively, the element is notrequired, both alternatives being within the scope of the claim. Use ofbroader terms such as comprises, includes, and having should beunderstood to provide support for narrower terms such as consisting of,consisting essentially of, and comprised substantially of. Accordingly,the scope of protection is not limited by the description set out abovebut is defined by the claims that follow, that scope including allequivalents of the subject matter of the claims. Each and every claim isincorporated as further disclosure into the specification and the claimsare embodiment(s) of the present invention.

What is claimed is:
 1. A heat exchanger for a furnace, comprising: atleast one heat exchanger tube; and a temperature protection sleevedisposed at least partially within the heat exchanger tube.
 2. The heatexchanger of claim 1, wherein the temperature protection sleevecomprises a flange and an elongated tube extending from the flange. 3.The heat exchanger of claim 2, wherein the temperature protection sleevecomprises a plurality of perforations disposed about the elongated tubeof the temperature protection sleeve.
 4. The heat exchanger of claim 3,wherein the temperature protection sleeve is configured to shield atleast a portion of the heat exchanger tube from at least one of a flameand an elevated temperature flue product produced from combusting apre-mixed air-fuel mixture within the furnace.
 5. The heat exchanger ofclaim 3, wherein the temperature protection sleeve is configured todissipate heat generated from combusting a pre-mixed air-fuel mixture.6. The heat exchanger of claim 2, wherein the flange of the temperatureprotection sleeve is disposed between a burner of the furnace and aninlet of the at least one heat exchanger tube.
 7. The heat exchanger ofclaim 6, wherein the flange of the temperature protection sleeve ismounted to a partition panel of the furnace.
 8. The heat exchanger ofclaim 7, wherein at least a portion of the inlet of the at least oneheat exchanger tube is captured by the flange of the temperatureprotection sleeve.
 9. The heat exchanger of claim 3, wherein the atleast one heat exchanger tube complies with ANSI Z21.47.
 10. The heatexchanger of claim 9, wherein the furnace is configured to emit lessthan 14 Nanograms of oxides of nitrogen per Joule (Ng/J) of heatdelivered to a temperature conditioned area.
 11. The heat exchanger ofclaim 10, wherein the furnace complies with SCAQMD Rule
 1111. 12. Afurnace, comprising: at least one burner; and a heat exchanger,comprising: at least one heat exchanger tube; and a temperatureprotection sleeve disposed at least partially within the heat exchangertube.
 13. The furnace of claim 12, wherein the temperature protectionsleeve comprises a flange and an elongated tube extending from theflange.
 14. The furnace of claim 13, wherein the temperature protectionsleeve comprises a plurality of perforations disposed about theelongated tube of the temperature protection sleeve.
 15. The furnace ofclaim 14, wherein the temperature protection sleeve is configured toshield at least a portion of the heat exchanger tube from at least oneof a flame and an elevated temperature flue product produced fromcombusting a pre-mixed air-fuel mixture within the furnace.
 16. Thefurnace of claim 14, wherein the temperature protection sleeve isconfigured to dissipate heat generated from combusting a pre-mixedair-fuel mixture with the at least one burner.
 17. The furnace of claim12, wherein at least a portion of the inlet of the at least one heatexchanger tube is captured by the flange of the temperature protectionsleeve, and wherein the flange of the temperature protection sleeve isdisposed between the at least one burner of the furnace and an inlet ofthe at least one heat exchanger tube.
 18. The furnace of claim 14,wherein the at least one heat exchanger tube complies with ANSI Z21.47.19. The furnace of claim 18, wherein the furnace is configured to emitless than 14 Nanograms of oxides of nitrogen per Joule (Ng/J) of heatdelivered to a temperature conditioned area and wherein the furnacecomplies with SCAQMD Rule
 1111. 20. The furnace of claim 19, wherein thefurnace is a component of a heating, ventilation, and/or airconditioning (HVAC) system.